Protectors for electric circuits



United States Patent ABSTRACT OF THE DISCLOSURE An insulating memberadjacent the line contact of a holder for electric fuses keeps theterminal of an electric fuse from electrically engaging that contactuntil that terminal has moved the forward face of that insulating memberrearwardly relative to that contact.

This invention relates to improvements in protectors for electriccircuits. More particularly, this invention relates to improvements inholders for electric fuses.

It is, therefore, an object of the present invention to provide animproved fuse holder.

It is frequently desirable to dispose electric fuses within holders thatcan fully enclose those fuses and thereby protect persons and nearbyobjects from engagement with electrically live parts of those fuses. Onesuch fuse holder that has been found to be extremely useful anddesirable has a two-section housing of insulating material, and eachsection of that housing has a contact located within a recess therein.In using that fuse holder, the user thereof can force one terminal of afuse into a cuplike contact which is located within the recess in one ofthe sections of that fuse holder and which is connected to the load sideof the circuit, and can then use that one section of that fuse holder tomove that fuse into engagement with a contact which is located withinthe recess in the other section of that fuse holder and which isconnected to the line side of that circuit. Prior to the time theterminal of that fuse engages the contact which is connected to the lineside of the circuit, the two sections of the fuse holder will completelyenclose that fuse and will thereby keep the fingers or hands of the userof that fuse holder from engaging an electrically live part of thatfuse. As a result, the said fuse holder is extremely useful anddesirable.

If the user of such a fuse holder failed to follow standard electricalpractice, and thus failed to use the one section of the fuse holder andthe cup-like contact therein to move a fuse into engagement with theline contact in the other section of the fuse holderand, instead, usedhis fingers to move that fuse into engagement with that line contact-hemight receive a shock. It would be desirable to provide a fuse holderwhich could keep even those persons who fail to follow standardelectrical practice, as they insert fuses into fuse holders, fromreceiving electrical shocks. The present invention provides such a fuseholder; and it does so by mounting a member of insulation forwardly ofthe contact, in the other section of the fuse holder, which is connectedto the line side of the circuit. That member of insulation willintercept the fuse before that fuse can move far enough into the othersection of the fuse holder to receive suflicient support from thatsection to be held by that section. As a result, that fuse will fallaway from that section of the fuse holder, and will thus be kept frombecoming electrically live. It is, therefore, an object of the presentinvention to provide a fuse holder which mounts a member of insulationforwardly of the contact, in the other section of the fuse holder, thatis connected to the line side of the circuit, and which requires thatmember of insulation to be moved or compressed by the inner terminal ofa fuse before that inner terminal can engage that contact.

Other and further objects and advantages of the present invention shouldbecome apparent from an examination of the drawing and accompanyingdescription.

In the drawing and accompanying description two preferred embodiments ofthe present invention are shown and described but it is to be understoodthat the drawing and accompanying description are for the purpose ofillustration only and do not limit the invention and that the inventionwill be defined by the appended claims.

In the drawing, FIG. 1 is a front elevational view of one preferredembodiment of fuse holder that is made in accordance with the principlesand teachings of the present invention,

FIG. 2 is a sectional view, on a larger scale, through the fuse holderof FIG. 1, and it is taken along the plane indicated by the line 22 inFIG. 1,

FIG. 3 is a sectional view, on the scale of FIG. 2, it is taken alongthe plane indicated by the line 22 in FIG. 1, and it shows the left-handportion of the fuse holder as it appears when the fuse has been removedfrom that fuse holder,

FIG. 4 is a partially broken-away, front elevational view of part of afuse holder that is similar to the fuse holder of FIG. 1 but which has adifferent movable contact,

FIG. 5 is another partially broken-away, front elevational view of thefuse holder of FIG. 4, and it shows that fuse holder as it appears whenthe fuse has been removed, and

FIG. 6 is a sectional view through the fuse holder of FIG. 4, and it istaken along the plane indicated by the line 66 in FIG. 5.

Referring to the drawing in detail, the numeral generally denotes onepreferred embodiment of fuse holder that is made in accordance with theprinciples and teachings of the present invention. That fuse holder hasa body portion 22 of generally cylindrical form which has a cylindricalrecess 24 therein. A wall 26 is provided at the right-hand end of thecylindrical recess 24, and the left-hand end of that recess is open. Apassage 28 is provided in the wall 26; and an annular recess 30 isprovided in the outer face of that wall, and that recess communicateswith that passage. An annular shoulder 32, of generally rectangularcross section, is formed on the exterior of the body portion 22; andthat annular shoulder is closer to the left-hand end of that bodyportion than it is to the right-hand end of that body portion, as shownparticularly by FIG. 2. A shallow annular rib 34 is formed on theexterior of the body portion 22 a short distance to the right of theannular shoulder 32. The body portion 22 is preferably formed from aninexpensive but tough plastic material; and phenolic resins constituteplastic materials which are very useful in forming that body portion.

The numeral 38 denotes a terminal which has a flanged inner face 40; anda short portion of the length of that terminal is dimensioned to fitsnugly within the passage 28 in the wall 26 of the body portion 22,while the flanged inner face 40 is dimensioned so it cannot pass throughthat passage. The terminal 38 also has an elongated shank with anelongated recess 46 therein. A cup-like contact 42 has an opening in theclosed end thereof through which the shank and the short portion of theterminal 38 extends; but the flanged inner face 40 of that terminal istoo large to pass through that opening. The flanged inner face 40 of theterminal 38 is used to press the cup-like contact 42 against the wall 26of the body portion 22; and then the periphery of the outer face of theshort portion of that terminal will be staked or riveted into theannular recess 30 in that body portion to fixedly secure that terminaland that contact to each other and to that body portion.

A sleeve 48 of heat-shrinkable insulation is telescoped over the shankof the terminal 38; and that sleeve extends into the annular recess 30in the body portion 22 to abut the short portion of that terminal. Thatsleeve is shrunk into intimate engagement with the terminal 38 bysuitable application of heat.

A sealing material 50, such as an epoxy resin, is used to fill theannular recess 30 in the right-hand end of the body member 22. Thatsealing member provides a watertight seal between that body member andthe terminal 38.

The numeral 52 denotes an internally-threaded nut; and that nut has anend wall 54 with a large opening therein. The smallest diameter of thethread of the internallythreaded nut 52 is large enough to enable thatnut to freely telescope over the annular shoulder 32 on the body portion22; but the diameter of the opening in the end wall 54 of thatinternally-threaded nut is smaller than the diameter of that annularshoulder. As a result, that end wall can abut and bear against theright-hand face of the annular shoulder 32 on the body member 22, asshown by FIG. 2; and, in abutting and bearing against that annularshoulder, that wall can prevent further movement of theinternally-threaded nut 52 to the left in FIG. 2. The diameter of theopening in the end wall 54 of the internally-threaded nut 52 is veryclose to the diameter of the shallow annular rib 34 at the exterior ofthe body portion 22; and, as a result, an appreciable force must beapplied to the internally-threaded nut 52 to cause the opening in theend wall 54 thereof to slip over that annular rib. Thereafter, thatshallow annular rib will pre- I A wall 60 is provided at the left-handof the recess 58, I

and the other end of that recess communicates with a larger-diametercylindrical recess 72 in the body portion 156. The recess 72 is in alarger-diameter section 71 of that body portion; and that recess opensto the righthand end of that body portion. The recess 72 is dimensionedto telescope over the left-hand end of the body portion 22 as shown byFIG. 2. An abrupt annular shoulder 70 is provided intermediate thelarger diameter section 71 of the body portion 156 and the rest of thatbody portion. A passage 62 is provided in the wall 60 of the bodyportion 156; and an annular recess 64 is provided in the outer face ofthat wall, and that recess co mmunicates with that passage. A shallowannular rib 66 is formed on the exterior of the body portion 156 a shortdistance to the left of the annular shoulder 70. The body portion 156 ispreferably formed from an inexpensive but tough plastic material, andphenolic resins constitute plastic materials which are very useful informing that body portion.

The numeral 176 denotes a terminal which has a flanged inner face 178;and a short portion of that terminal is dimensioned to fit snugly withinthe passage 62 in the wall 60 of the body portion 156, while the flangedinner face. 178 is dimensioned so it cannot pass through that passage.The terminal 176 has a rivet-like shank 181 extending beyond the passage62 in the end wall 60 of the body portion 156; and that rivet-like shankextends through a passage in the end wall of an elongated, cup-like,terminal extension 179. A sealing material 192, such as an epoxy resin,is disposed within the annular recess 64 in the left-hand face of thewall 60 of the body portion 156; and that sealing material provides awater-tight seal between the terminal 176 and the body portion 156.After the sealing material 192 has hardened, the passage in the end wallof the terminal extension 179 is telescoped over the shank 181 of theterminal 176; and then the outer end of that shank is riveted over topermanently secure that terminal extension to that terminal. Solder 183is then applied to the riveted-over inner end of the shank 181 and tothe interior of the terminal extension 179 to electrically bond themtogether. Thereafter, a sleeve 190 of heat-shrinkable material istelescoped over the exterior of the terminal extension 179 and over aconsiderable portion of the exterior of the body portion 156, and thenthat sleeve is shrunk into intimate engagement with that terminalextension and that body portion. That sleeve will keep moisture,corrosive fumes, salt spray, or the like from reaching the junctionbetween the terminal 176 and the terminal extension 179.

The numeral 94 denotes an externally-threaded nut; and the thread onthat nut is formed and dimensioned to mate with the thread on theinternally-threaded nut 52. The nut 94 has an end wall 98 with a largeopening therein; and the inner diameter of that nut is large enough toenable that nut to telescope freely over the large-diameter section 71of the body portion 156, but the diameter of the opening in the end wall98 of that nut is smaller than the diameter of that larger-diametersection. As a result, the end wall 98 can abut and bear against theshoulder on the body portion 156, and can thereby prevent furthermovement of the nut 94 to the right in FIG. 2. The diameter of theopening in the end wall 98 of the nut 94 is very close to the diameterof the shalow, annular rib 66, at the exterior of the body member 156;and, as a result, an appreciable force must be applied to the nut 94 tocause the opening in the end wall 98 thereof to slip over that annularrib. Thereafter, that shallow, annular rib will prevent accidentalseparation of the nut 94 from the body portion 156.

The internally-threaded nut 52 and the externallythreaded nut 94 arepreferably made from a tough material which is capable of having strongthreads formed thereon. One such material is nylon. Both of the nuts 52and 94 have polygonal wrench-receiving surfaces at the exteriorsthereof; and those surfaces enable wrenches to grip and tighten thosenuts.

The numeral 200 denotes a movable contact which is located within therecess 58 in the body portion 156; and that movable contact is generallycylindrical in form. An annular projection 201 extends from theleft-hand face of that movable contact, and that annular projectionaccommodates one end of a flexible conductor 84; and the other end ofthat flexible conductor is embedded within a recess in the terminal 176.Solder is used to bond the ends of the flexible conductor 84 to theterminal 176 and to the movable contact 200.

A helical compression spring 88 surrounds theflexible conductor 84; andthe left-hand end of that spring bears against the flanged inner face178 of the terminal 176, while the right-hand end of that spring bearsagainst the left-hand face of the movable contact 200. A compressionspring 204 has the left-hand end thereof disposed within a cylindricalrecess 202 in the right-hand face of the movable contact 200, and hasthe right-hand end thereof surrounding and intimately engaging acylindrical projection at the left-hand face of an insulator 206.Preferably, the left-hand end of the spring 204 has a larger diameterthan the right-hand end of that spring. The insulator 206 is dimensionedso it can telescope within the recess 202 in the movable contact 200;and, preferably, that insulator is circular in end view. The spring 204urges the insulator 206 to the extended position shown by FIG. 3,

but that spring can yield to permit that insulator to move within therecess 202 in the movable contact 200, as shown particularly by FIG. 2.

The numeral denotes an electric fuse which is dimensioned to telescopewithin the cylindrical recesses 24 and 58, respectively, in the bodyportions 22 and 156. That fuse has ferrule-like terminals at theopposite ends thereof; and one of those terminals will extend into, and

be held by, the cup-like contact 42, while the other of those terminalswill abut the insulator 206 and can abut the annular right-hand end ofthe movable contact 200. The cup-like contact 42 will grip theright-hand terminal of the fuse 100, and it will apply such strongholding forces to that terminal that an appreciable force will have tobe applied to the fuse 100 to free it from that cup-like contact. Suchholding forces are desirable, because they will prevent accidentalseparation of the fuse 100 from the cup-like contact 42.

The numeral 102 denotes an O-ring which is made from a resilientmaterial. That O-ring is dimensioned to telescope over the left-hand endof the body portion 22 and to abut the left-hand face of the annularshoulder 32 on that body portion. The O-ring 102 will be engaged by theright-hand end face of the larger diameter section 71 of the bodyportion 156.

In using the fuse holder of FIGS. 1-3, the insulationfree end of aconductor, not shown, which is connected to the line side of anelectrical circuit is telescoped within the terminal extension 179, andthen a crimping tool is used to crimp that terminal extension tightlyonto that end of that conductor. Thereafter, field-installed insulation,such as splicing compound electrical tape, friction tape, or the like,is used to cover the insulation-free portion of that terminal extensionand the insulation-free portion of that conductor. The sleeve 190 ofinsulation will not only perform an insulating function but will alsoserve as a surface to which the field-installed insulation will readilyadhere.

The insulation-free end of a conductor, not shown, which is connected tothe load side of the electrical circuit is telescoped within the recess46 and the terminal 38; and then a crimping tool is used to crimp theshank of that terminal tightly onto that end of that conductor.Thereafter, field-installed insulation, such as splicing compound,electrical tape, friction tape, or the like is used to cover theinsulation-free portion of the shank of terminal 38 and theinsulation-free portion of the end of that conductor. The sleeve 48 ofinsulation will not only perform an insulating function but will alsoserve as a surface to which the field-installed insulation will readilyadhere.

A fuse 100 is then telescoped into the cylindrical recess 24 in the bodyportion 22, and the inner terminal of that fuse is pressed into thecup-like contact 42 until that inner terminal abuts the flanged innerface 40 of the terminal 38. The outer terminal of the fuse 100 willproject outwardly beyond the end of the body portion 22; but the user ofthe fuse holder 120 cannot receive a shock if he touches that fusetenminal; because the cup-like contact 42 and the terminal 38 willconnect that fuse to the load side rather than to the line side of theelectrical circuit.

The user of the fuse holder 120 will then align the recess 24 in thebody portion 22 with the recess 58 in the body portion 156; and willmove those body portions toward each other. The outer terminal of thefuse 100 will be moved into and through the cylindrical recess 72 in thelarger-diameter section 71 of the body portion 156, and will then bemoved into the cylindrical recess 58 in that body portion. As the outerterminal of the fuse 100 moves through the recess 72, the insulator 206will receive that outer terminal and will keep that outer terminal fromimmediately engaging the movable contact 200. Not until the outerterminal of the fuse 100 has moved all the way through the recess 72 andhas entered the recess 58 can that outer terminal of that fuse closelyapproach the movable contact 200. By the time the outer terminal of thefuse 100 engages the movable contact 200, the left-hand end of the bodyportion 52 will have telescoped within the outer end of the cylindricalrecess 72 in the larger-diameter section 71 of the body portion 156.This is important; because it makes absolutely certain that any arewhich could form as the fuse 100 engaged the movable contact 200 wouldbe wholly enclosed and could not injure the user of the fuse holder, andbecause it makes absolutely certain that the outer terminal of the fuse100 is completely enclosed by the body portions 22 and 156 before thatouter terminal can engage the live movable contact 200.

As shown by the drawing, the diameter of the wire of which the spring204 is formed is smaller than the diameter of the wire of which thespring 88 is formed. As a result, the spring 204 will yield and willpermit the insulator 206 to move wholly within the recess 202 in themovable contact 200 before the spring 88 is compressed to anyappreciable extent. The yielding nature of the spring 204 is important;because it makes certain that the insulator 206 will permit the outerterminal of the fuse 100 to seat solidly against the annular right-handend of the movable contact 200 and provide the intimate engagement whichis required to minimize contact resistance between that movable contactand that outer terminal.

As the left-hand end of the body portion 22 is telescoped within thecylindrical recess 72 in the largerdiameter section 71 of the bodyportion 156, the nut 52 will be rotated to force the external thread onthe nut 94- to move inwardly of the internal thread on the nut 52. Theend walls 54 and 98, respectively, of the nuts 52 and 94 will be forcedtoward each other; and those end walls will act through the shoulders 32and to force the left-hand face of the shoulder 32 toward the righthandend of the larger-diameter section 71 of the body portion 156. Theleft-hand face of that shoulder and that right-hand face of thatlarger-diameter section will abut and compress the O-ring 102, therebyforming a tight seal between themselves and that O-ring.

As the end walls 54 and 98, respectively, of the nuts 52 and 94 areforced to move toward each other, the lefthand terminal of the fuse willforce the movable contact 200 to move toward the position shown by FIG.2. The flexible conductor 84 and the helical compression spring 88 willboth yield to permit that contact to move toward that position. However,the helical compression spring 88 will develop strong restorative forcestherein which will hold the right-hand face of the movable contact 200in intimate engagement with the left-hand terminal of the fuse 100.

Whenever the fuse 100 is to be inspected or replaced, it is onlynecessary to rotate the nut 52 in the reverse direction until the nut isfreed from the nut 94, to move the body portion 22 away from the bodyportion 156, and to withdraw the fuse 100 from its position within therecess 24 in the body portion 22. If an arc tends to form as theleft-hand terminal of the fuse 100 is moved away from the movablecontact ZOO-and such an arc could form if the fuse 100 was intact andthe fuse holder was opened while that fuse was carrying current that arcwould be initiated and could be extinguished while the left-hand end ofthe body portion 22 was disposed within the cylindrical recess 72 in thelargerdiameter section 71 of the body portion 156. As a result, that arecould be confined and need not injure the user of the fuse holder 120.

Prior to the time the left-hand end of the body portion 22 moves out ofthe recess 72 in the larger-diameter section 71 of the body portion 156,the compression .spring 204 and the insulator 206 will have forced theend of the fuse 100 away from the movable contact 200. This is desirablebecause it makes certain that the outer terminal of that fuse could notremain in engagement with the movable contact 200, and thus makescertain that neither of the terminals of that fuse could be electricallylive. As a result, even if, somehow, the fuse 100 could remain in therecess 72 of the body portion 156, instead of moving with the bodyportion 22, that fuse would not be electrically live and would thus notconstitute a hazard to the user of the fuse holder.

The spring 204 and the insulator 206 also can protect the user of thefuse holder 120 from shock in the event that user should try to use hisfingers to insert the electric fuse 100 directly into the body portion156. If that user should try to insert the fuse 100 into the bodyportion 156, the left-hand terminal of that fuse would be intercepted bythe insulator 206 before that left-hand terminal could enter the recess58 in that body portion. A fuse that was stopped short of the recess 58in the body portion 156 could not receive sufficient support from thatbody portion to be held by that body portion; and, instead, would fallaway from that body portion. As a result, any such fuse would be keptfrom becoming electrically live.

FIGS. 46 show a different form of movable contact and member ofinsulation for the fuse holder 120. Thus, FIGS. 46 show a movablecontact 220 which has an annular projection 201 at the left-hand facethereof, to receive the right-hand end of the flexible conductor 84, andwhich has a cylindrical projection 221 at the righthand face thereof. Amember 222 of insulation is secured to and carried by the movablecontact 220; and that member preferably is made from a yieldableinsulating material such as synthetic rubber. That member is annular inform, and it encircles the cylindrical projection 221 on the movablecontact 220.

The member 222, in its unstressed state, is thicker than the cylindricalprojection 221 on the movable contact 220; but the material of whichthat member is made is sufficiently resilient to enable the thickness ofthat member to be reduced to a value less than that of the cylindricalportion 221. This means that whenever a fuse 100 is introduced into thebody portion 22 of the fuse holder, and then has the left-hand terminalthereof introduced into the body portion 156, the left-hand terminal ofthat fuse will engage the member 222 before it can engage thecylindrical projection 221 on the movable contact 220. However, as thenuts 52 and 94 are tightened, the member 222 will become compressed andwill permit the lefthand terminal of the fuse to move into intimateelectrical engagement with the cylindrical projection 221 on I themovable contact 20.

The member 222 of insulation will perform the functions performed by theinsulator 206 and the spring 204 shown in FIGS. 13. Specifically, thatmember will keep any part of the fuse 100 from becoming electricallylive until after the left-hand end of the body portion 22 has telescopedinto the recess 72 in the larger-diameter section 71 of the body portion156, and thus has made sure that the fuse holder has completely enclosedthat fuse. Furthermore, that member can keep a user from being shockedif he inadvertently attempts to insert an electric fuse 100 directlyinto the body portion 156, rather than introduce that fuse into the bodyportion 22 and then use that body portion to introduce that fuse intothe body portion 156. In addition, the member 222 will push theleft-hand terminal of the electric fuse 100 away from the movablecontact 220 prior to the time the left-hand end of the body portion 22is moved out of the recess 72 in the body portion 156. The member 222has been shown as an annulus surrounding the cylindrical projection 221on the movable contact 220; but that member could be mounted adjacent afixed contact and it could be given other configurations. For example,that member could be made as a cylindrical pad which was held within arecess in a stationary contact. Regardless of the configuration giventhe member 222, and regardless of the contact with which it is used,that member should have an unstressed dimension which would enable it tointercept the terminal of a fuse being moved toward'that contact andshould have a stressed dimension which would enable that terminal ofthat fuse to intimately engage that contact.

The fuse holders shown in FIGS. 1-6 are known as in line fuse holders;and such fuse holders are very useful. The present invention also isusable with fuse holders that are known as post type fuse holdersthemember of insulation being mounted forwardly of the contact that isconnected to line.

Whereas the drawing and accompanying description have shown anddescribed two preferred embodiments of the present invention, it shouldbe apparent to those skilled in the art that various changes may be madein the form of the invention without affecting the scope thereof.

What I claim is:

1. A holder for electric fuses which comprises:

a housing with a recess therein dimensioned to receive one of theterminals of an electric fuse,

a contact that is disposed within said recess and that is connectable tothe line side of an electric circuit,

said contact being disposed inwardly of said recess and said housingguiding said terminal of said electric fuse toward said contact wheneversaid terminal of said electric fuse is telescoped into said recess,

a second contact that is connectable to the load side of said electriccircuit, and

an insulating member that is disposed forwardly of the first saidcontact and that normally blocks engagement between said terminal ofsaid electric fuse and said first said contact as said terminal of saidelectric fuse is telescoped into said recess,

said insulating member having a forward face which is movable rearwardlyrelative to said first said contact by said terminal of said electricfuse and is disposed forwardly of said first said contact and which mustbe engaged by said terminal of said electric fuse before said terminalof said electric fuse can engage said first said contact as saidterminal of said electric fuse is telescoped into said recess,

said forward face of said insulating member being movable rearwardly bysaid terminal of said electric fuse until said terminal engages andmakes an electrical connection with said first said contact of said fuseholder and thus with said line side of said electric circuit as saidterminal of said electric fuse is telescoped into said recess.

2. A holder for electric fuses which comprises:

a housing with a recess therein dimensioned to receive one of theterminals of an electric fuse,

a contact that is disposed within said recess and that is connectable tothe line side of an electric circuit,

said contact being disposed inwardly of said recess and said housingguiding said terminal of said electric fuse toward said contact wheneversaid terminal of said electric fuse is telescoped into said recess,

a second contact that is connectable to the load side of said electriccircuit,

an insulating member that is disposed forwardly of the first saidcontact and that normally blocks engagement between said terminal ofsaid electric fuse and said first contact as said terminal of saidelectric fuse is telescoped into said recess,

said insulating member having a forward face which is movable rearwardlyrelative to said first said contact by said terminal of said electricfuse and is disposed forwardly of said first contact and which must beengaged by said terminal of said electric fuse before said terminal ofsaid electric fuse can engage said first said contact as said terminalof said electric fuse is telescoped into said recess,

said forward face of said insulating member being movable rearwardly bysaid terminal of said electric fuse until said terminal engages andmakes an electrical connection with said first said contact of said fuseholder and thus with said line side of said electric circuit as saidterminal of said electric fuse is telescoped into said recess,

said housing supporting said contacts,

said housing having separable sections,

said first said contact being located within one of said sections,

said second contact being located within another of said sections, and

said insulating member being located inwardly of said one section ofsaid housing.

3. A holder for electric fuses which comprises:

a housing with a recess therein dimensioned to receive one of the theterminals of an electric fuse,

a contact that is disposed within said recess and that is connectable tothe line side of said electric circuit,

said contact being disposed inwardly of said recess and said housingguiding said terminal of said electric fuse toward said contact wheneversaid terminal of said electric fuse is telescoped into said recess,

a second contact that is connectable to the load" side of said electriccircuit,

an insulating member that is disposed forwardly of the first saidcontact and that normally blocks engagement between said terminal ofsaid electric fuse and said first said contact as said terminal of :saidelectric fuse is telescoped into said recess,

said insulating member having a forward face which is movable rearwardlyrelative to said first said contact by said terminal of said electricfuse and is disposed forwardly of said first said contact and which mustbe engaged by said terminal of said electric fuse before said terminalof said electric fuse can engage said first said contact as saidterminal if said electric fuse is telescoped into said recess,

said forward face of said insulating member being movable rearwardly bysaid terminal of said electric fuse until said terminal engages andmakes an electrical connection with said first said contact of said fuseholder and thus with said line side of said electric circuit as saidterminal of said electric fuse is telescoped into said recess,

said first said contact being movably mounted within said housing, and

said forward face of said insulating member moving, in response toengagement by said terminal of said fuse before said first said contactmoves appreciably.

4. A holder for electric fuses which comprises:

a housing with a recess therein dimensioned to receive one of theterminals of an electric fuse,

a contact that is disposed within said recess and that is connectable tothe line side of an electric circuit,

said contact being disposed inwardly of said recess and said housingguiding said terminal of said electric fuse toward said contact wheneversaid terminal of said electric fuse is telescoped into said recess,

a second contact. that is connectable to the load side of said electriccircuit,

an insulating member that is disposed forwardly of the first saidcontact and that normally blocks engagement between said terminal ofsaid electric fuse and said first said contact as said terminal of saidelectric fuse is telescoped into said recess,

said insulating member having a forward face which is movable rearwardlyrelative to said first said contact by said terminal of said electricfuse and is disposed forwardly of said first said contact and which mustbe engaged by said terminal of said electric fuse before said terminalof said electric fuse can engage said first said contact as saidterminal of said electric fuse is telescoped into said recess,

said forward face of said insulating member being movable rearwardly bysaid terminal of said electric fuse until said terminal engages andmakes an electrical connection with said first said contact of said fuseholder and thus with said line side of said electric circuit as saidterminal of said electric fuse is telescoped into said recess,

a compressible element normally displacing said insulating memberforwardly of said first said contact but being compressible to permitsaid insulating member to be moved rearwardly toward said first saidcontact.

5. A holder for electric fuses which comprises:

a housing with a reces therein dimensioned to receive one of theterminals of an electric fuse,

a contact that is disposed within said recess and that is connectable tothe line side of an electric circuit,

\said contact being disposed inwardly of said recess and said housingguiding said terminal of said electric fuse toward said contact wheneversaid terminal of said electric fuse is telescoped into said recess,

a second contact that is connectable to the load side of said electriccircuit,

an insulating member that is disposed forwardly of the first saidcontact and that normally blocks engagement between said terminal ofsaid electric fuse and said first said contacts as said terminal of saidelectric fuse is telescoped into said recess,

said insulating member having a forward face which is movable rearwardlyrelative to said first said contact by said terminal of said electricfuse and is disposed forwardly of said first said contact and which mustbe engaged by said terminal of said electric fuse before said terminalof said electric fuse can engage said first said contact as saidterminal of said electric fuse is telescoped into said recess.

said forward face of said insulating member being movable rearwardly bysaid terminal of said electric fuse until said terminal engages andmakes an electrical connection with said first said contact of said fuse'holder and thus with said line side of said electric circuit as saidterminal of said electric fuse is telescoped into said recess,

said first said contact having a recess therein, and

said insulating member being dimensioned to be telescoped into saidrecess in said first said contact.

6. A holder for electric fuses which comprises:

a housing with a recess therein dimensioned to receive one of theterminals of an electric fuse,

a contact that is disposed within said recess and that is connectable tothe line side of an electric circuit,

said contact being disposed inwardly of said recess and said housingguiding said terminal of said electric fuse toward said contact wheneversaid terminal of said electric fuse is telescoped into said recess,

a second contact that is connectable to the load side of said electriccircuit,

an insulating member that is disposed forwardly of the first saidcontact and that normally blocks engagement between said terminal ofsaid electric fuse and said first said contacts as said terminal of saidelectric fuse is telescoped into said recess.

said insulating member having a forward face which is movable rearwardlyrelative to said first said contact by said terminal of said electricfuse and is disposed forwardly of said first said contact and which mustbe engaged by said terminal of said electric fuse before said terminalof said electric fuse can engage said first said contact as saidterminal of said electric fuse is telescoped into said recess,

said forward face of said insulating member being movable rearwardly bysaid terminal of said electric fuse until said terminal engages andmakes an electrical connection with said first said contact of said fuseholder and thus with said line side of said electric circuit as saidterminal of said electric fuse is telescoped into said recess,

said insulating member being readily compressible,

said insulating member having an unstressed dimension that will enableit to keep said terminal of said electric fuse from engaging said firstsaid contact but being adapted to have a compressed dimension that willenable it to permit said terminal of said electric fuse to engage saidfirst said contact.

7. A holder for electric fuses which comprises:

a housing with a recess therein dimensioned to receive one of theterminals of an electric fuse,

a contact that is disposed within said recess and that is connectable tothe line side of an electric circuit,

said contact being disposed inwardly of said recess and said housingguiding said terminal of said electric fuse toward said contact wheneversaid terminal of said electric fuse is telescoped into said recess,

a second contact that is connectable to the load side of said electriccircuit,

an insulating member that is disposed forwardly of the first saidcontact and that normally blocks engagement between said terminal ofsaid electric fuse and said first said contacts as said terminal of saidelectric fuse is telescoped into said recess,

said insulating member having a forward face which is movable rearwardlyrelative to said first said contact by said terminal of said electricfuse and is disposed forwardly of said first said contact and which mustbe engaged by said terminal of said electric fuse before said terminalof said electric fuse can engage said first said contact as saidterminal of said electric fuse is telescoped into said recess.

said forward face of said insulating member being movable rearwardly bysaid terminal of said electric fuse until said terminal engages andsnakes an electrical connection with said first said contact of saidfuse holder and thus with said line side of said electric circuit assaid terminal of said electric fuse is telescoped into said recess,

said first said contact being movably mounted within said housing, and

said forward face of said insulating member being movable relative tosaid first said contact,

said forward face of said insulating member initially responding toengagement by said terminal of said electric fuse to move relative tosaid first said contact and then subsequently said insulating member andsaid firs-t said cont-act moving relative to said housing.

8. A holder for electric fuses which comprises:

a housing with a recess therein dimensioned to receive one of theterminals of an electric fuse,

a contact that is disposed within said recess and that is connectable tothe line side of an electric circuit,

said contact being disposed inwardly of said recess and said housingguiding said terminal of said electric fuse toward said contact wheneversaid terminal of said electric fuse is telescoped into said recess,

a second contact that is connectable to the load side of said electriccircuit,

an insulating member that is disposed forwardly of the first saidcontact and that normally blocks engagement between said terminal ofsaid electric fuse and said first said contacts as said terminal of saidelectric fuse is telescoped into said recess,

said insulating member having a forward face which is movable rearwardlyrelative to said first said contact by said terminal of said electricfuse and is disposed forwardly of said first said contact and which mustbe engaged by said terminal of said electric fuse before said terminalof said electric fuse can engage said first said contact as saidterminal of said electric fuse is telescoped into said recess,

said forward face of said insulating member being movable rearwardly bysaid terminal of said electric fuse until said terminal engages andmakes an electrical connection with said first said contact of said fuseholder and thus with said line side of said electric circuit as saidterminal of said electric fuse is telescoped into said recess,

said insulating member being initially spaced from said first saidcontact by a spring, and

said spring responding to the force supplied to said insulating memberby said electric fuse to yield and thereby permit said insulating memberand said terminal of said electric fuse to move toward said first saidcontact.

9. A holder for electric fuses which comprises:

a housing with a recess therein dimensioned to receive one of theterminals of an electric fuse,

a contact that is disposed within said recess and that is connectable tothe line side of an electric circuit,

said contact being disposed inwardly of said recess and said housingguiding said terminal of said electric fuse toward said contact wheneversaid terminal of said electric fuse is telescoped into said recess,

a second contact that is connectable to the load side of said electriccircuit,

an insulating member that is disposed forwardly of the first saidcontact and that normally blocks engagement between said terminal ofsaid electric fuse and said first said contacts as said terminal of saidelectric fuse is telescoped into said recess,

said insulating member having a forward face which is movable rearwardlyrelative to said first said contact by said terminal of said electricfuse and is disposed forwardly of said first said contact and which mustbe engaged by said terminal of said electric fuse before said terminalof said electric fuse can engage said first sai-d contact as saidterminal of said electric fuse is telescoped into said recess,

said forward face of said insulating member being movable rearwardly bysaid terminal of said electric fuse until said terminal engages andmakes an electrical connection with said first said contact of said fuseholder and thus with said line side of said electric circuit as saidterminal of said electric fuse is telescoped into said recess,

said insulating member being annular in form and surrounding aforwardly-extending projection on said first said contact,

said insulating member having an unstressed dimension that will enableit to keep terminal of said electric fuse from engaging said forwardlyextending projection on said first said contact but being adapted tohave a compressed dimension that will enable it to permit said terminalof said electric fuse to engage said forwardly-extending projection onsaid first said contact.

10. A holder for electric fuses which comprises:

a housing with a recess therein dimensioned to receive one of theterminals of an electric fuse,

a contact that is disposed within said recess and that is connectable tothe line side of an electric circuit,

said contact being disposed inwardly of said recess and said housingguiding said terminal of said electric fuse toward said contact wheneversaid terminal of said electric fuse is telescoped into said recess,

a second contact that is connectable to the load side of said electriccircuit,

an insulating member that is disposed forwardly of the first saidcontact and that normally blocks engagement between said terminal ofsaid electric fuse and said first said contacts as said terminal of saidelectric fuse is telescoped into said recess,

said insulating member having a forward face which is movable rearwardlyrelative to said first said contact by said terminal of said electricfuse and is disposed forwardly of said first said contact and which mustbe engaged by said terminal of said electric fuse before said terminalof said electric fuse can engage said first said contact as saidterminal of said electric fuse is telescoped into said recess,

said forward face of said insulating member being movable rearwardly bysaid terminal of said electric fuse until said terminal engages andmakes an electrical connection with said first said contact of said fuseholder and thus with said line side of said electric circuit as saidterminal of said electric fuse is telescoped into said recess,

said first said contact being movably mounted within said housing, and

said insulating member being readily compressible,

said insulating member having an unstressed dimension that will enableit to keep said terminal of said electric fuse from engaging said firstsaid contact but being adapted to have a compressed dimension that willenable it to permit said terminal of said electric fuse to engage saidfirst said contact.

said insulating member initially responding to engagement by saidterminal of said electric fuse to assume said compressed dimension andthen subsequently said insulating member and said first said contactmoving relative to said housing.

1,833,173 11/1931 Murray 200-153 Beck et al. 200118 Stender et al200-118 Gilley 200153 Bulgin 200-129 X Urani 200-129 BERNARD A.GILHEANY, Primary Examiner. H. B. GILSON, Assistant Examiner.

US. Cl. X.R.

